How is unit converter calculated?

The formula, a worked example and the assumptions are shown on this page. Results are estimates for planning, not financial, medical or legal advice.

Is this unit converter calculator free to use?

Yes. It runs entirely in your browser, needs no account and stores nothing on a server.

Unit Converter

Q: How this is calculated

Unit converter — how this is calculated. This page shows the formula, a worked example and the assumptions behind the result.

Length, weight, and volume — metric and imperial.

How this is calculated

Every unit is converted to a common base (meters for length, kilograms for weight, liters for volume) and then to the target unit, using standard conversion factors.

Worked examples

5 kilometres to miles: 5 ÷ 1.609344 = 3.11 miles. 70 kilograms to pounds: 70 × 2.20462262 = 154.32 pounds. 2 litres to US fluid ounces: 2 × 33.814023 = 67.63 fluid ounces. 100 degrees Celsius to Fahrenheit: (100 × 9 ÷ 5) + 32 = 212°F.

Common conversion factors

Length: 1 inch = 2.54 cm exactly; 1 foot = 30.48 cm; 1 mile = 1.609344 km
Weight: 1 pound = 0.45359237 kg; 1 ounce = 28.349523 g
Volume: 1 US gallon = 3.78541178 litres; 1 litre = 33.814023 US fluid ounces
Temperature: °F = (°C × 9 ÷ 5) + 32; K = °C + 273.15

Rounding depends on the precision you need. For engineering work, carry more decimal places than you display, and check the conversion factor against an authoritative source before relying on it for a purchase or a safety decision.